Many different microscopic techniques are utilized in the development of new pharmaceuticals. For that reason, pharmaceutical companies have supported microscopy and microscopists even in the face of retrenchments in many other industries. Microscopy has the following three major uses in pharmaceutical development: 1) solid-state characterization of drug substance; 2) particle size analysis; 3) contaminant identification. Microscopy is also an important component of the study of the biological activity of drugs but that subject will not be discussed here.

The analysis of the solid-state properties of new drug candidates is probably the most important and challenging subject of study for pharmaceutical microscopists.1 The primary objective of these studies is identification of the most suitable solid-state form (i.e. polymorph, solvate, hydrate) of the drug substance for development. Polarized light microscopy (PLM), thermal microscopy (TM), infrared microspectroscopy (IR), and Raman microspectroscopy (RM) are all utilized in these studies. Both PLM and TM are used to discover new polymorphs and solvates of the chemical.